A new PBS documentary upends what producers say is the widely accepted notion that the Emancipation Proclamation ended slavery in this country.

Author Douglas Blackmon gave the film its factual heft.

Blackmon visited Savannah several times in recent years to discuss his central theme.

Former Atlanta-Journal Constitution author Blackmon spent years researching his book.

"Slavery by Another Name" lends its title to the documentary.

Blackmon says, while chattel slavery ended with the Civil War, thousands of African-Americans were bought, sold, mistreated and forced to work without pay in a de facto slavery that lingered until about World War Two.

"The truth that is evident in these thousands of pages of records resets the clock on the whole debate about how long African-Americans have had to recover from the setbacks of slavery," Blackmon told a Savannah audience.

Speaking in Savannah at the Jepson Center for the Arts and at the Ralph Mark Gilbert Savannah Civil Rights Museum, Blackmon called the era a story of American failure.

"The truth is, there are thousands of African-Americans alive today who were born into a state of de facto slavery on some farm in South Georgia, Alabama, Florida, Mississippi or Louisiana in the 1930's or the early 1940's," Blackmon says.